This should do the job for you:
Qualtrics.SurveyEngine.addOnReady(function(){
    const qid = this.questionId;
    var okay_choices = y];
    
    that = this;
    this.questionclick = function(){
        sel_choices = that.getSelectedChoices();
        // Set the maximum number of choices you want here
        if(sel_choices.length <=3){
            okay_choices = sel_choices;
        }
        else{
            alert("You can not select more than 3 choices.\\nPlease deselect to select another.");
            sel_choices.forEach((item) => {
                Qualtrics.SurveyEngine.registry�qid].setChoiceValue(item,false);
                });
            okay_choices.forEach((item) => {
                Qualtrics.SurveyEngine.registrysqid].setChoiceValue(item,true);
                });
        }


    }
});

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This is EXACTLY what I was looking for. Thank you!

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Will this javascript not work for 2 questions in a row? Here is what I have in for Q6 and Q7 but it is only working for Q7.

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Too eager to celebrate were we. :-)
It appears that the variables are being shared across the questions and hence this will only work for the last question in which code is inserted. To make it work for all, you'll need to rename the variables (

qid

,

that

,

okay_choices

) for each question. You can change them to anything like (

qid1

,

qid2

,

qid3 

etc.) Just make sure, they are unique for each question. Here's how it should look finally:
Qualtrics.SurveyEngine.addOnReady(function(){
    const qid1 = this.questionId;
    var okay_choices1 = 1];
    
    that1 = this;
    this.questionclick = function(){
        sel_choices = that1.getSelectedChoices();
        // Set the maximum number of choices you want here
        if(sel_choices.length <=3){
            okay_choices1 = sel_choices;
        }
        else{
            alert("You can not select more than 3 choices.\\nPlease deselect to select another.");
            sel_choices.forEach((item) => {
                Qualtrics.SurveyEngine.registryrqid1].setChoiceValue(item,false);
                });
            okay_choices1.forEach((item) => {
                Qualtrics.SurveyEngine.registry.qid1].setChoiceValue(item,true);
                });
        }


    }
   
});

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Hi @ahmedA 

This worked well.

But do we have any further options to improve this?

Ideally removing the vanity URL and ‘says’.

 

Or some nicer looking Qualtrics warning message?

Thanks :)

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Customizations will be chargable, drop me a PM if interested.

Thanks.

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